fix #316: omit export default of local type

CHANGELOG.md

@@ -12,6 +12,10 @@
 
     The cache holds a maximum of 5 entries and purges least-recently-used entries above that limit.
 
+* Omit `export default` of local type names ([#316](https://github.com/evanw/esbuild/issues/316))
+
+    Normally the `export default` syntax takes a value expression to export. However, TypeScript has a special case for `export default <identifier>` where the identifier is allowed to be a type expression instead of a value expression. In that case, the type expression should not be emitted in the resulting bundle. This release improves support for this case by omitting the export when the identifier matches a local type name.
+
 ## 0.6.16
 
 * Colors for Windows console output

internal/bundler/bundler_ts_test.go

@@ -1007,3 +1007,211 @@ console.log(all_default, all_computed_default, a, b, c, d, e_default2, f_default
 		},
 	})
 }
+
+func TestTSExportDefaultTypeIssue316(t *testing.T) {
+	expectBundled(t, bundled{
+		files: map[string]string{
+			"/entry.ts": `
+				import dc_def, { bar as dc } from './keep/declare-class'
+				import dl_def, { bar as dl } from './keep/declare-let'
+				import im_def, { bar as im } from './keep/interface-merged'
+				import in_def, { bar as _in } from './keep/interface-nested'
+				import tn_def, { bar as tn } from './keep/type-nested'
+				import vn_def, { bar as vn } from './keep/value-namespace'
+				import vnm_def, { bar as vnm } from './keep/value-namespace-merged'
+
+				import i_def, { bar as i } from './remove/interface'
+				import ie_def, { bar as ie } from './remove/interface-exported'
+				import t_def, { bar as t } from './remove/type'
+				import te_def, { bar as te } from './remove/type-exported'
+				import ton_def, { bar as ton } from './remove/type-only-namespace'
+				import tone_def, { bar as tone } from './remove/type-only-namespace-exported'
+
+				export default [
+					dc,
+					dl,
+					im,
+					_in,
+					tn,
+					vn,
+					vnm,
+
+					i,
+					ie,
+					t,
+					te,
+					ton,
+					tone,
+				]
+			`,
+			"/keep/declare-class.ts": `
+				declare class foo {}
+				export default foo
+				export let bar = 123
+			`,
+			"/keep/declare-let.ts": `
+				declare let foo: number
+				export default foo
+				export let bar = 123
+			`,
+			"/keep/interface-merged.ts": `
+				class foo {
+					static x = new foo
+				}
+				interface foo {}
+				export default foo
+				export let bar = 123
+			`,
+			"/keep/interface-nested.ts": `
+				if (true) {
+					interface foo {}
+				}
+				export default foo
+				export let bar = 123
+			`,
+			"/keep/type-nested.ts": `
+				if (true) {
+					type foo = number
+				}
+				export default foo
+				export let bar = 123
+			`,
+			"/keep/value-namespace.ts": `
+				namespace foo {
+					export let num = 0
+				}
+				export default foo
+				export let bar = 123
+			`,
+			"/keep/value-namespace-merged.ts": `
+				namespace foo {
+					export type num = number
+				}
+				namespace foo {
+					export let num = 0
+				}
+				export default foo
+				export let bar = 123
+			`,
+			"/remove/interface.ts": `
+				interface foo { }
+				export default foo
+				export let bar = 123
+			`,
+			"/remove/interface-exported.ts": `
+				export interface foo { }
+				export default foo
+				export let bar = 123
+			`,
+			"/remove/type.ts": `
+				type foo = number
+				export default foo
+				export let bar = 123
+			`,
+			"/remove/type-exported.ts": `
+				export type foo = number
+				export default foo
+				export let bar = 123
+			`,
+			"/remove/type-only-namespace.ts": `
+				namespace foo {
+					export type num = number
+				}
+				export default foo
+				export let bar = 123
+			`,
+			"/remove/type-only-namespace-exported.ts": `
+				export namespace foo {
+					export type num = number
+				}
+				export default foo
+				export let bar = 123
+			`,
+		},
+		entryPaths: []string{"/entry.ts"},
+		options: config.Options{
+			IsBundling:    true,
+			AbsOutputFile: "/out.js",
+		},
+		expected: map[string]string{
+			"/out.js": `// /keep/declare-class.ts
+var declare_class_default = foo;
+let bar = 123;
+
+// /keep/declare-let.ts
+var declare_let_default = foo;
+let bar2 = 123;
+
+// /keep/interface-merged.ts
+class foo2 {
+}
+foo2.x = new foo2();
+let bar3 = 123;
+
+// /keep/interface-nested.ts
+if (true) {
+}
+var interface_nested_default = foo;
+let bar4 = 123;
+
+// /keep/type-nested.ts
+if (true) {
+}
+var type_nested_default = foo;
+let bar5 = 123;
+
+// /keep/value-namespace.ts
+var foo4;
+(function(foo5) {
+  foo5.num = 0;
+})(foo4 || (foo4 = {}));
+let bar6 = 123;
+
+// /keep/value-namespace-merged.ts
+var foo3;
+(function(foo5) {
+  foo5.num = 0;
+})(foo3 || (foo3 = {}));
+let bar7 = 123;
+
+// /remove/interface.ts
+let bar8 = 123;
+
+// /remove/interface-exported.ts
+let bar9 = 123;
+
+// /remove/type.ts
+let bar10 = 123;
+
+// /remove/type-exported.ts
+let bar11 = 123;
+
+// /remove/type-only-namespace.ts
+let bar12 = 123;
+
+// /remove/type-only-namespace-exported.ts
+let bar13 = 123;
+
+// /entry.ts
+var entry_default = [
+  bar,
+  bar2,
+  bar3,
+  bar4,
+  bar5,
+  bar6,
+  bar7,
+  bar8,
+  bar9,
+  bar10,
+  bar11,
+  bar12,
+  bar13
+];
+export {
+  entry_default as default
+};
+`,
+		},
+	})
+}

internal/parser/parser.go

@@ -66,6 +66,7 @@ type parser struct {
 	emittedNamespaceVars       map[ast.Ref]bool
 	isExportedInsideNamespace  map[ast.Ref]ast.Ref
 	knownEnumValues            map[ast.Ref]map[string]float64
+	localTypeNames             map[string]bool
 
 	// Imports (both ES6 and CommonJS) are tracked at the top level
 	importRecords               []ast.ImportRecord
@@ -3954,7 +3955,7 @@ func (p *parser) parseStmt(opts parseStmtOpts) ast.Stmt {
 				case "type":
 					// "export type foo = ..."
 					p.lexer.Next()
-					p.skipTypeScriptTypeStmt(parseStmtOpts{isExport: true})
+					p.skipTypeScriptTypeStmt(parseStmtOpts{isModuleScope: opts.isModuleScope, isExport: true})
 					return ast.Stmt{Loc: loc, Data: &ast.STypeScript{}}
 
 				case "namespace", "abstract", "module":
@@ -4185,7 +4186,13 @@ func (p *parser) parseStmt(opts parseStmtOpts) ast.Stmt {
 		}
 
 		p.lexer.Next()
+		name := p.lexer.Identifier
 		p.lexer.Expect(lexer.TIdentifier)
+
+		if opts.isModuleScope {
+			p.localTypeNames[name] = true
+		}
+
 		p.skipTypeScriptTypeParameters()
 
 		if p.lexer.Token == lexer.TExtends {
@@ -4880,7 +4887,7 @@ func (p *parser) parseStmt(opts parseStmtOpts) ast.Stmt {
 					case "type":
 						if p.lexer.Token == lexer.TIdentifier {
 							// "type Foo = any"
-							p.skipTypeScriptTypeStmt(parseStmtOpts{})
+							p.skipTypeScriptTypeStmt(parseStmtOpts{isModuleScope: opts.isModuleScope})
 							return ast.Stmt{Loc: loc, Data: &ast.STypeScript{}}
 						}
 
@@ -5839,6 +5846,16 @@ func (p *parser) visitAndAppendStmt(stmts []ast.Stmt, stmt ast.Stmt) []ast.Stmt
 		case s.Value.Expr != nil:
 			*s.Value.Expr = p.visitExpr(*s.Value.Expr)
 
+			// Discard type-only export default statements
+			if p.TS.Parse {
+				if id, ok := (*s.Value.Expr).Data.(*ast.EIdentifier); ok {
+					symbol := p.symbols[id.Ref.InnerIndex]
+					if symbol.Kind == ast.SymbolUnbound && p.localTypeNames[symbol.Name] {
+						return stmts
+					}
+				}
+			}
+
 		case s.Value.Stmt != nil:
 			switch s2 := s.Value.Stmt.Data.(type) {
 			case *ast.SFunction:
@@ -8587,6 +8604,7 @@ func newParser(log logging.Log, source logging.Source, lexer lexer.Lexer, option
 		emittedNamespaceVars:      make(map[ast.Ref]bool),
 		isExportedInsideNamespace: make(map[ast.Ref]ast.Ref),
 		knownEnumValues:           make(map[ast.Ref]map[string]float64),
+		localTypeNames:            make(map[string]bool),
 
 		// These are for handling ES6 imports and exports
 		importItemsForNamespace: make(map[ast.Ref]map[string]ast.LocRef),

internal/parser/parser_ts.go

@@ -668,7 +668,13 @@ func (p *parser) skipTypeScriptTypeStmt(opts parseStmtOpts) {
 		return
 	}
 
+	name := p.lexer.Identifier
 	p.lexer.Expect(lexer.TIdentifier)
+
+	if opts.isModuleScope {
+		p.localTypeNames[name] = true
+	}
+
 	p.skipTypeScriptTypeParameters()
 	p.lexer.Expect(lexer.TEquals)
 	p.skipTypeScriptType(ast.LLowest)
@@ -820,6 +826,9 @@ func (p *parser) parseTypeScriptNamespaceStmt(loc ast.Loc, opts parseStmtOpts) a
 	// real export either.
 	if len(stmts) == importEqualsCount || opts.isTypeScriptDeclare {
 		p.popAndDiscardScope(scopeIndex)
+		if opts.isModuleScope {
+			p.localTypeNames[nameText] = true
+		}
 		return ast.Stmt{Loc: loc, Data: &ast.STypeScript{}}
 	}
 

internal/printer/printer.go

@@ -471,13 +471,6 @@ func (p *printer) addSourceMapping(loc ast.Loc) {
 	}
 	originalLine--
 
-	if originalLine == -1 {
-		fmt.Printf("crash in file %s\n", p.options.SourceForSourceMap.PrettyPath)
-		fmt.Printf("lookup %d\n", loc.Start)
-		fmt.Printf("length %d\n", len(lineOffsetTables))
-		fmt.Printf("first %d\n", lineOffsetTables[0].byteOffsetToStartOfLine)
-	}
-
 	// Use the line to compute the column
 	line := &lineOffsetTables[originalLine]
 	originalColumn := int(loc.Start - line.byteOffsetToStartOfLine)